1. Field of the Invention
The present invention relates to a motor, and more particularly, to a connection structure between a conductive line which is drawn from a coil and a terminal.
2. Description of the Related Art
U.S. Pat. No. 7,884,514 shows a conventional motor including three terminals. Each terminal includes a U-shaped hook, and a single conductive line which is drawn from a coil group is sequentially wound around the U-shaped hook and is welded. Thereby, each terminal and the conductive line are electrically connected to each other.
In a winding process in which a coil is formed, it is necessary to wind the conductive line around teeth of a stator core without being loose. Thereby, sufficient tension to prevent looseness of the conductive line needs to be applied to the conductive line.
In the case of the motor of U.S. Pat. No. 7,884,514, since the conductive line is wound around a hook of the terminal in the course of the winding process, the tension of the conductive line is also applied to the hook. Accordingly, the hook needs sufficient strength to endure the tension of the conductive line without becoming permanently deformed or broken.
For example, when output efficiency of the motor is improved, it is considered that electric resistance is decreased by increasing the diameter of the conductive line. However, if the diameter of the conductive line is increased, stiffness of the conductive line is also increased in proportion to the increased diameter, and the tension which is applied to the conductive line in the winding process is also increased.
Accordingly, in the case of the conventional motor of U.S. Pat. No. 7,884,514, if the diameter of the conductive line is increased, disadvantages such as the need to strengthen the terminal or limitation of the diameter of the conductive line occur since there is a concern that deformation or damage of the hook may occur.
Moreover, in the case of the conventional motor of U.S. Pat. No. 7,884,514, there is a disadvantage at the time of the connection. Generally, welding between the conductive line and the terminal is performed by so-called fusion welding. In the fusion welding, the conductive line is clamped between terminals by a pair of electrodes, and the conductive line is welded by the pressing force and resistance heating which is generated by applying current between the electrodes.
When the conductive line is wound around the hook, the conductive line tends to strongly contact both corners of the hook. Thereby, when the fusion welding is performed, the resistance heating is unevenly distributed at both corners and there is a concern that the conductive line may be broken because the conductive line is welded too much in both corners. As a result, irregularity in the welding strength occurs, and there is a concern that connection failure or breaking of the wire may occur.
In addition, in the case of the conventional motor of U.S. Pat. No. 7,884,514, there is also a disadvantage after the connection. For example, in the case of an on-vehicle motor or the like used in an environment in which a great vibration is constantly applied, since the conductive line is welded to the terminal in a state where tension is applied, particularly, the welded portion is easily damaged by the action of an external force.